Japan's Sony Corp and Olympus Corp have again delayed the start of a joint venture to develop medical equipment because they have yet to gain approval from some regulators. "The examination by the relevant authority is taking longer than expected," the two companies said in a statement. They did not set a new date for operations to start. Plans by the Japanese companies to establish a joint venture to design and build medical devices have struggled to win approval in China, according to a source at one of the corporations familiar with the matter. Neither Sony or Olympus have said where they are still awaiting permission from regulators.